So I created a new client and for this client i created a new website and a new FTP-user.
Now the problem is, that this FTP-user can not login. I tried both passive and active conenctions. I even tried a local connection on the server.

Thats ok, pure-ftpd is able to connect to the database and gets some valid results. Please check with:

grep web2 /etc/passwd

and

grep client1 /etc/group

if the group and user exist. If they dont exist, then edit the website were the ftp user belongs to, e.g. change the quota and click on save. Then wait a minute and check again. You can see in the jobqueue of the monitor if the changes have been applied or if threre were any errors.

By the way, I changed the server name in /etc/hosts and /etc/hostname after the installation of ISPConfig3.

But I also changed the server name in "System -> Edit Server" and in "System -> Server Config" I changed the Network Configuration (checkbox "Network Configuration" is selected and the new hostname i correct).

Is there a tutorial how to install ISPconfig from SVN and more precisely, to make future use of SVN in order to update the installation?

Click to expand...

No. Especially as you normally should not use a svn version as its for development and might contain bugs or even destroy your setup. But in your case the fix is not released yet, so there are not so many options to solve it beside using the svn version.